Plate crossbow correction device and plate crossbow correction method

ABSTRACT

Each of the moving blocks of the plate crossbow correction device includes distance sensors and electromagnets, and plate crossbow is corrected by adjusting electromagnetic force by the electromagnets in accordance with distances to strips. The moving blocks are movable in the horizontal direction and ratios of moving distances of the moving blocks are adjusted to be constant when seen from a central position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plate crossbow correction device anda plate crossbow correction method.

2. Description of the Related Art

A hot-dip galvanizing line is a facility for plating successive steelplates (hereinafter referred to as “strips”) with molten metal. Ahot-dip galvanizing line is provided with a plate crossbow correctiondevice. In this respect, a plate crossbow correction device is alsoreferred to as a damping device.

Here, explanations will be made about steps for plating molten metal tothe strips in the hot-dip galvanizing line shown in FIG. 16 and FIG. 17.

As shown in FIG. 16 and FIG. 17, in a hot-dip galvanizing line 10,strips 2 are successively infiltrated into molten metal (molten platingbath) 1 and by winding the strips 2 around a sink roll 3 disposed in themolten metal 1, the running direction of the strips 2 is changed to anupward direction. After making in-bath rolls (support rolls) 4 a 4 bcontact both surfaces of the strips 2 (front surfaces and back surfacesof the strips) running in an upward direction, the strips 2 are pulledout from the molten metal 1. Air is sprayed from a wiping nozzle 5towards both surfaces of the strips 2 which have been pulled out and arerunning in the upward direction to remove excess molten metal. A platecrossbow correction device 6 is disposed upward of the wiping nozzle 5and the strips 2 run upward upon passing the plate crossbow correctiondevice 6.

The plate crossbow correction device 6 suppresses vibration of thestrips 2 by applying electromagnetic force (suction force) towards thestrips 2 and corrects crossbow of the strips 2 in a contactless manner.Details of the plate crossbow correction device 6 will be describedlater.

Here, explanations will now be made about crossbow occurring in strips 2and steps for correction the crossbow in such a hot-dip galvanizing line10.

When the strips 2 are wound around the sink roll 3, C crossbow (plasticcrossbow), which is crossbow deformation in a plate width direction,occurs in the strips 2. Therefore, the in-bath rolls 4 a, 4 b are madeto contact both surfaces of the strips 2 in which the C crossbow hasoccurred for correcting the C crossbow. Further, C crossbow is correctedby the plate crossbow correction device 6 by applying electromagneticforce to the strips 2.

By correcting C crossbow in this manner, the distance of the wipingnozzle 5 and the strips 2 will become substantially identical atrespective positions in the plate width direction (horizontal direction)of the strips 2 and the removal amount of molten metal by the wipingnozzle 5 will become substantially identical at respective positions inthe plate width direction. Thus, the amount of plating adhering to thestrips 2 can be made uniform.

The plate crossbow correction device 6 includes a correction mechanism6F on the front surface side disposed to be apart from the front surfaceof a strip 2 and a correction mechanism 6B on the back surface sidedisposed to be apart from the back surface of the strip 2.

The correction mechanism 6F on the front surface side comprises aplurality of (in this example, three) electromagnets M aligned in theplate width direction and a plurality of (in this example, three)distance sensors S aligned in the plate width direction. The distancesensors S are disposed at upward positions of the electromagnets M.Similarly to the correction mechanism 6F on the front surface side, thecorrection mechanism 6B on the back surface side is also provided with aplurality of (in this example, three) electromagnets M and a pluralityof (in this example, three) distance sensors S.

The electromagnets M provided in the correction mechanism 6F on thefront surface side and the electromagnets M provided in the correctionmechanism 6B on the back surface side are respectively disposed tooppose each other with the strips 2 being interposed between.

The distance sensors S detect distances between themselves and thestrips 2. A control device (not shown) controls current values suppliedto the electromagnets M such that the distances detected by the distancesensors S become a set distance to thereby adjust electromagnetic forceof the electromagnets M applied to the strips 2. With this arrangement,crossbow of the strips 2 is corrected in a contactless manner andvibration of the strips 2 is suppressed.

Now, it might happen that the strips travel while meandering. Therefore,in the technology of Patent Literature 1 (Japanese Utility ModelApplication Laid-Open Publication No. H 5-30148), the plate crossbowcorrection device (correction mechanism) is controlled to move in aplate width direction (horizontal direction) to follow the meandering.

Namely, in the technology of Patent Literature 1, plate width edgepositions, which are positions of ends in the plate width direction ofthe strips, are detected and the entire plate crossbow correction deviceis controlled to move in the plate width direction (horizontaldirection) as a whole in accordance with the detected plate width edgepositions.

Further, the strips might not only meander but also their plate widthsmight change. Therefore, in the technology of Patent Literature 2(Japanese Patent Application Laid-Open Publication No. 2001-106405),plate width edge positions on both ends which are both end positions inthe plate width direction of the strips are detected, and in accordancewith the detected plate width edge positions on both ends, one pair ofelectromagnets disposed on one end side (for instance, the right endside) and another pair of electromagnets disposed on the other end side(for instance, the left end side) from among electromagnets disposed inthe plate crossbow correction device (correction mechanism) arecontrolled and independently moved in the plate width direction(horizontal direction) in accordance with the detected plate width edgepositions. In this respect, a pair of electromagnets indicate a magnetdisposed on the front surface side of a strip and a magnet disposed onthe back surface side opposing the magnet on the front surface side.

In the technology shown in Patent Literature 2, positions of disposingelectromagnets which are disposed at positions other than those at bothends in the plate width direction are fixed and are not moved in theplate width direction (horizontal direction).

In this manner, in the technology shown in Patent Literature 2, a pairof electromagnets disposed on one end side and a pair of electromagnetsdisposed on the other end side are controlled and independently moved inthe plate width direction (horizontal direction) in accordance with theplate width edge positions so that it is possible to suitably correct Ccrossbow of the strips even though the strips meander or their platewidth change.

Now, according to the technology shown in Patent Literature 1, while itis possible to perform plate crossbow correction operations even thoughthe strips meander, it is not possible to suitably correct platecrossbow when plate widths of the strips change.

Further, according to the technology shown in Patent Literature 2,correction operations of plate crossbow are performed even though thestripes meander or plate widths of the strips change.

However, according to the technology shown in Patent Literature 2,positions of disposing electromagnets are fixed and not moved in theplate width direction in case of electromagnets disposed at positionsother than the both ends in the plate width direction so that intervalsof disposing a plurality of electromagnets aligned in the plate widthdirection become inappropriate and the crossbow of the strips mightbecome large.

Further, as shown in Patent Literature 2, even when the electromagnetsdisposed on both end sides (one end side and the other end side) arecontrolled to be moved in the plate width direction (horizontaldirection) in accordance with the plate width edge positions, thecrossbow of the strips might become large at both end portions when theelectromagnets at both end sides are not correctly opposing the endportions of the strips.

This situation will be explained with reference to FIG. 18 and FIG. 19.In this respect, in FIG. 18 and FIG. 19, x indicates the plate widthdirection and z indicates a direction from the front surface sidetowards the back surface side of a strip.

FIG. 18 shows a crossbowed state of a strip at a position of a distancesensor disposed in the plate crossbow correction device, wherein thehorizontal axis shows the plate width direction position while thevertical axis shows the plate shape (amount of crossbow). The solid linein FIG. 18 shows a crossbowed state of a strip after crossbow correctionand the dotted line in FIG. 18 shows a crossbowed state of a strip whenno crossbow correction has been performed.

FIG. 19 shows a crossbowed state of a strip at a position of a wipingnozzle disposed in the plate crossbow correction device, wherein thehorizontal axis shows the plate width direction position while thevertical axis shows the plate shape (amount of crossbow). The solid linein FIG. 19 shows a crossbowed state of a strip after crossbow correctionand the dotted line in FIG. 19 shows a crossbowed state of a strip whenno crossbow correction has been performed.

As shown by the solid lines in FIG. 18 and FIG. 19, it can be understoodthat the crossbow at both end portions of the strip are large even afterperforming crossbow correction using electromagnets when theelectromagnets on both end sides are not correctly opposing end portionsof the strip.

In view of the above prior art, the present invention aims to provide aplate crossbow correction device and a plate crossbow correction methodcapable of reliably reducing crossbow at positions in the plate widthdirection of the strips including both end portions of the strips evenwhen strips meander or their plate widths change.

SUMMARY OF THE INVENTION

The plate crossbow correction device according to the first invention ofthe present application for solving the above subject is a platecrossbow correction device including:

a correction mechanism on a front surface side disposed on a frontsurface side of a conveyed steel plate which adjusts electromagneticforce applied to the steel plate in accordance with a distance to thesteel plate and corrects crossbow of the steel plate, and

a correction mechanism on a back surface side disposed on a back surfaceside of the conveyed steel plate which adjusts electromagnetic forceapplied to the steel plate in accordance with a distance to the steelplate and corrects crossbow of the steel plate,

wherein the correction mechanism on the front surface side and thecorrection mechanism on the back surface side respectively comprise

a plurality of moving blocks comprised with distance sensors detecting adistance to the steel plate and electromagnets applying electromagneticforce to the steel plate,

a guide structure supporting the plurality of blocks to be movable alonga plate width direction of the steel plate, and

a moving structure moving a moving block close to an end portion of thesteel plate from among the plurality of moving blocks along the guidestructure and moving the remaining blocks along the guide structurefollowing the moving block close to the end portion of the steel plate.

The plate crossbow correction device according to the second inventionof the present invention application is characterized in that

in the first invention,

the moving mechanism includes a servomotor and a rack and pinionmechanism transmitting driving force of the servomotor to the pluralityof moving blocks and moving the plurality of moving blocks.

The plate crossbow correction device according to the third invention ofthe present invention application is characterized in that

in the second invention,

the rack and pinion mechanism is arranged in that the gear ratio isdetermined such that moving distances each of the moving blocks movewhen seen from a central position of the plate crossbow correctiondevice become a distance which is in accordance with a preliminarilydetermined stroke ratio.

The plate crossbow correction device according to the fourth inventionof the present invention application is characterized in that

any one of the first to third inventions further comprises

a plate edge sensor detecting plate width edge positions which arepositions at ends in the plate width direction of the steel plate, and

a control unit controlling moving operations of the moving mechanismsuch that a moving block close to an end portion of the steel platesfrom among the plurality of moving blocks opposes the plate width edgeposition.

The plate crossbow correction device according to the fifth invention ofthe present invention application is characterized in that it furtherincludes

an overall moving mechanism on the front surface side moving thecorrection mechanism on the front surface side of any one of the firstto fourth inventions along the plate width direction of the steel plate,and

an overall moving mechanism on the back surface side moving thecorrection mechanism on the back surface side of any one of the first tofourth inventions along the plate width direction of the steel plate.

A plate crossbow correction method according to the sixth invention is aplate crossbow correction method by a plate crossbow correction device,

wherein a correction mechanism on a front surface side disposed on afront surface side of a conveyed steel plate which adjustselectromagnetic force applied to the steel plate in accordance with adistance to the steel plate and corrects crossbow of the steel plate,and

a correction mechanism on a back surface side disposed on a back surfaceside of the conveyed steel plate which adjusts electromagnetic forceapplied to the steel plate in accordance with a distance to the steelplate and corrects crossbow of the steel plate, respectively include

a plurality of moving blocks comprised with distance sensors detecting adistance to the steel plate and electromagnets applying electromagneticforce to the steel plate, and

a guide structure supporting the plurality of blocks to be movable alonga plate width direction of the steel plate,

wherein a moving block close to an end portion of the steel plate fromamong the plurality of moving blocks is moved along the guide structureand the remaining moving blocks are moved along the guide structurefollowing movements of the moving block close to the end portion of thesteel plate.

The plate crossbow correction method according to the seventh inventionis characterized in that

in the sixth invention,

the plurality of moving blocks are moved such that moving distances eachof the moving blocks move when seen from a central position of the platecrossbow correction device become a distance which is in accordance witha preliminarily determined stroke ratio.

The plate crossbow correction method according to the eighth inventionis characterized in that

in the sixth or seventh invention,

plate width edge positions which are positions at ends in the platewidth direction of the steel plate are detected, and

a moving block close to an end portion of the steel plate from among theplurality of moving blocks is moved to a position opposing the platewidth edge position.

According to the present invention, since the remaining moving blocksare moved following movements of the moving blocks close to the endportions of the steel plates, it is possible to reliable reduce crossbowof steel plates even when steel plates meander or their plate widthschange.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a hot-dip galvanizing line comprising theplate crossbow correction device according to the first embodiment ofthe present invention.

FIG. 2 is a side view showing the hot-dip galvanizing line comprisingthe plate crossbow correction device according to the first embodimentof the present invention.

FIG. 3 is a front view when a correction mechanism on a front surfaceside in a widened state is seen from the strip side.

FIG. 4 is a front view when the correction mechanism on the frontsurface side in a narrowed state is seen from the strip side.

FIG. 5 is a sectional view including an A-A section of FIG. 3.

FIG. 6 is a sectional view including a B-B section of FIG. 3.

FIG. 7A is a plan view showing a moving mechanism in a widened state.

FIG. 7B is a plan view showing a moving mechanism in a widened state.

FIG. 8 A is a plan view showing the moving mechanism in a narrowedstate.

FIG. 8 B is a plan view showing the moving mechanism in a narrowedstate.

FIG. 9 is a characteristic diagram showing a crossbowed state of a stripat a position at which a distance sensor is disposed in the firstembodiment.

FIG. 10 is a characteristic diagram showing a crossbowed state of astrip at a position at which a wiping nozzle is disposed in the firstembodiment.

FIG. 11 is a characteristic diagram showing a crossbowed state of astrip after crossbowing correction at the position at which the distancesensor is disposed in a plate crossbow correction device comprising fivepairs of electromagnets.

FIG. 12 is a characteristic diagram showing a crossbowed state of astrip after crossbowing correction at the position at which the wipingnozzle is disposed in the plate crossbow correction device comprisingfive pairs of electromagnets.

FIG. 13 is a characteristic diagram showing a relationship betweennumbers of pairs of electromagnets and plate crossbow at the position atwhich the wiping nozzle is disposed.

FIG. 14 is a plan view showing the plate crossbow correction deviceaccording to the second embodiment of the present invention.

FIG. 15 is a front view when the plate crossbow correction deviceaccording to the second embodiment of the present invention is seen fromthe strip side.

FIG. 16 is a front view showing a hot-dip galvanizing line comprisingthe plate crossbow correction device of the prior art.

FIG. 17 is a side view showing the hot-dip galvanizing line comprisingthe plate crossbow correction device of the prior art.

FIG. 18 is a characteristic diagram showing a crossbowed state of astrip at a position at which a distance sensor is disposed according tothe prior art.

FIG. 19 is a characteristic diagram showing a crossbowed state of astrip at a position at which a wiping nozzle is disposed according tothe prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be explained in detailsbased on examples thereof.

First Embodiment

A hot-dip galvanizing line 10 a comprising a plate crossbow correctiondevice 100 according to the first embodiment of the present inventionwill be explained with reference to FIG. 1 which is a front view andFIG. 2 which is a side view.

In the hot-dip galvanizing line 10 a, strips 2 successively infiltratedinto molten metal 1 are wound around a sink roll 3 and the runningdirection is changed into an upward direction, similarly to the hot-dipgalvanizing line 10 shown in FIG. 16 and FIG. 17. After making in-bathrolls 4 a 4 b contact both surfaces of the strips 2, the strips 2 arepulled out from the molten metal 1, and air is sprayed from a wipingnozzle 5 towards both surfaces of the strips 2 to remove excess moltenmetal. A plate crossbow correction device 100 according to the presentembodiment is disposed upward of the wiping nozzle 5, and the strips 2run upward upon passing the plate crossbow correction device 100.

Explaining the outline of the plate crossbow correction device 100, theplate crossbow correction device 100 includes a correction mechanism100F on the front surface side disposed to be apart from the frontsurface of a strip 2 and a correction mechanism 100B on the back surfaceside disposed to be apart from the back surface of the strip 2.

The correction mechanism 100F on the front surface side comprises aplurality of (in this example, four) electromagnets M aligned in theplate width direction and a plurality of (in this example, four)distance sensors S aligned in the plate width direction. Similarly tothe correction mechanism 100F on the front surface side, the correctionmechanism 100B on the back surface side also comprises a plurality of(in this example, four) electromagnets M aligned in the plate widthdirection and a plurality of (in this example, four) distance sensors Saligned in the plate width direction. Moreover, the electromagnets Mprovided in the correction mechanism 100F on the front surface side andthe electromagnets M provided in the correction mechanism 100B on theback surface side are respectively disposed to oppose each other withthe strips 2 being interposed between.

Namely, the plate crossbow correction device 100 comprises four pairs ofelectromagnets M. While details will be explained later, the four pairsof electromagnets M are arranged to move in the plate width direction(horizontal direction) of the strips 2 in accordance with meanderings orchanges in plate widths of the strips 2 in order to suitably correctcrossbowing of the strips 2.

In this respect, when the distance sensors S on the front surface sideand the distance sensors S on the back surface side perform measurementat identical positions in the plate width direction, it is also possibleto omit either ones on one side of the distance sensors S on the frontsurface side and the distance sensors S on the back surface side.

A plate edge sensor 20 is disposed at an upward position of the platecrossbow correction device 100. The plate edge sensor 20 detects plateedge positions which are positions on one end (right end in the exampleof FIG. 1) in the plate width direction of the strips 2.

As it will be described later, a control device 30 controls positions inthe plate width direction of the four pairs of electromagnets M of theplate crossbow correction device 100 in accordance with plate width edgepositions detected by the plate edge sensor 20.

Next, details of the plate crossbow correction device 100 will beexplained.

FIG. 3 is a front view of the correction mechanism 100F on the frontside in a widened state seen from the strip side, FIG. 4 is a front viewof the correction mechanism 100F on the front side in a narrowed stateseen from the strip side, FIG. 5 is a sectional view including an A-Asection of FIG. 3, and FIG. 6 is a sectional view including a B-Bsection of FIG. 3. In this respect, for easy understanding, componentswhich are not illustrated in FIG. 3 are shown in FIG. 5 and FIG. 6.

In this respect, since machine configurations of the correctionmechanism 100F on the front side and the correction mechanism 100B onthe back side are identical, explanations will be made of the detailedconfiguration of the correction mechanism 100F on the front side onlywhile explanations of the detailed configuration of the correctionmechanism 100B on the back side will be omitted.

As shown in FIG. 3 to FIG. 6, a frame 102 extending in the plate widthdirection (horizontal direction) of the strips 2 is fixedly installed ata support beam 101.

The frame 102 is provided with four moving blocks 110-1, 110-2, 110-3and 110-4 aligned in the horizontal direction. While details will beexplained later, the moving blocks 110-1 to 110-4 are provided to bemovable in the horizontal direction along the frame 102. In thisrespect, reference numeral 110 is used when the four moving blocks 110-1to 110-4 are to be collectively referred to.

Each moving block 110 is provided with an electromagnet M and a distancesensor S of eddy current type. Namely, the electromagnet M is providedon a lower side of a support pole 111 of the moving block 110 and thedistance sensor S is provided on an upper side of the support pole 111(see FIG. 6). Namely, the distance sensor S is disposed at an upwardposition of the electromagnet M.

A lower support plate 112 is fixed to an upper end portion of thesupport pole 111 and an upper support plate 113 is disposed at an upwardposition of the lower support plate 112. The upper support plate 113 isattached to the lower support plate 112 via gears (pinions or the like)to be described later.

A linear rail 103 extending in the horizontal direction is provided on alower surface of the frame 102. A linear slider 104 is attached on anupper surface of the upper support plate 113 of each moving block 110.The linear slider 104 of the moving blocks 110 engages with the linearrail 103 in a freely sliding manner, and the linear rail 103 and thelinear sliders 104 constitute a linear guide (guide structure).

The moving blocks 110 are made movable in the horizontal direction bythe thus arranged linear guide (guide structure).

In this respect, the wiping nozzle 5 is attached to the frame 102 via asupport body 50 and is disposed at a downward position of the movingblocks 110.

Next, a moving mechanism 200 for moving the moving blocks 110 in thehorizontal direction will be explained.

The moving mechanism 200 is arranged to transmit driving force of aservomotor to the moving blocks 110 using a rack and pinion mechanismfor moving the moving blocks 110. Moreover, the rack and pinionmechanism is comprised of gear elements in mesh with other gear elementson an upper plane and gear elements in mesh with other gear elements ona lower plane with respect to the vertical direction.

In the following explanations, gear elements in mesh with other gearelements on the upper plane are marked with “reference numerals whichare numbers added with α” while gear elements in mesh with other gearelements on the lower plane are marked with “reference numerals whichare numbers added with β”.

FIG. 7A and FIG. 7B are plan views showing the moving mechanism 200provided in the correction mechanism 100F of the plate crossbowcorrection device 100 in a widened state, and FIG. 8A and FIG. 8B areplan views showing the moving mechanism 200 provided in the correctionmechanism 100F of the plate crossbow correction device 100 in a narrowedstate.

Further, in FIG. 7A and FIG. 8A, gear elements in mesh with other gearelements on the upper plane are shown by solid lines while gear elementsin mesh with other gear elements on the lower plane are shown by dottedlines. In FIG. 7B and FIG. 8B, gear elements in mesh with other gearelements on the lower plane are shown by solid lines while gear elementsin mesh with other gear elements on the upper plane are shown by dottedlines.

A driving source unit 205 is attached to the frame 102 at a centralportion in the horizontal direction of the correction mechanism 100F ofthe plate crossbow correction device 100. The driving source unit 205comprises a servomotor 206, and a drive gear 201β is provided at arotating shaft of the servomotor 206. The driving source unit 205 isprovided with a pinion gear 202β and a pinion gear 203β which mesh withthe drive gear 201β.

The moving block 110-1 is provided with a pinion gear 211α, an idlergear 212α which is in mesh with the pinion gear 211α and aspeed-increasing pinion gear 213α which is a two-stage gear formed of asmall-diameter gear and a large-diameter gear. The idler gear 212α is inmesh with the small-diameter gear of the speed-increasing pinion gear213α.

Lower end sides of rotating shafts of these gears 211α, 212α and 213αare supported by the lower support plate 112 through bearings and upperend sides of the rotating shafts are supported by the upper supportplate 113 through bearings.

The moving block 110-1 is provided with a movable rack 214β projectingto the driving source unit 205 side, and the movable rack 214β is inmesh with the pinion gear 202β. Moreover, the movable rack 214β issupported at the frame 102 in a movable manner by means of a linearguide for movable racks.

Moreover, a fixed rack 215α is fixed to the frame 102 proximate of themoving block 110-1. The fixed rack 215α is in mesh with the pinion gear211α.

The moving block 110-2 is provided with a movable rack 221α projectingto the moving block 110-1 side and the movable rack 221α is in mesh withthe large-diameter gear of the pinion gear 213α. Further, the movablerack 221α is supported at the frame 102 in a movable manner by means ofthe linear guide for movable racks.

The moving block 110-3 is provided with a pinion gear 231α, an idlergear 232α which is in mesh with the pinion gear 231α and aspeed-increasing pinion gear 233α which is a two-stage gear formed of asmall-diameter gear and a large-diameter gear. The idler gear 232α is inmesh with the small-diameter gear of the speed-increasing pinion gear233α.

Lower end sides of rotating shafts of these gears 231α, 232α and 233αare supported by the lower support plate 112 through bearings and upperend sides of the rotating shafts are supported by the upper supportplate 113 through bearings.

The moving block 110-3 is provided with a movable rack 234β projectingto the driving source unit 205 side, and the movable rack 234β is inmesh with the pinion gear 203β. Moreover, the movable rack 234β issupported at the frame 102 in a movable manner by means of the linearguide for movable racks.

Moreover, a fixed rack 235α is fixed to the frame 102 proximate of themoving block 110-3. The fixed rack 235α is in mesh with the pinion gear231α.

The moving block 110-4 is provided with a movable rack 241α projectingto the moving block 110-3 side and the movable rack 241α is in mesh withthe large-diameter gear of the pinion gear 233α. Moreover, the movablerack 241α is supported at the frame 102 in a movable manner by means ofthe linear guide for movable racks.

In the moving mechanism 200, the diameter of the pinion gears 202β,203β, 211α and 231α is D1, and in the speed-increasing pinion gears213α, 233α, the diameter of the large-diameter gears is D1 while thediameter of the small-diameter gears is D2. Namely, the gear ratio ofthe rack and pinion mechanism of the moving mechanism 200 is determinedby the diameter D1 and the diameter D2.

Next, operations of moving the moving blocks 110 in the horizontaldirection by driving the moving mechanism 200 will be explained.

When the driving gear 201β is rotated leftward by the servomotor 206 ofthe driving source unit 205 in the widened state as shown in FIG. 7A andFIG. 7B , the pinion gear 202β is rotated rightward and pulls themovable rack 214β to the driving source unit 205 side. With thisarrangement, the moving block 110-1 moves to the left.

When the moving block 110-1 moves to the left, the pinion gear 211 a inmesh with the fixed rack 215α rotates leftward, the idler gear 212αrotates rightward and the speed-increasing pinion gear 213α rotatesleftward. The leftward rotation of the speed-increasing pinion gear 213αpulls the movable rack 221α to the moving block 110-1 side. With thisarrangement, the moving block 110-2 moves to the left.

Further, when the driving gear 201β is rotated leftward by theservomotor 206 of the driving source unit 205 in the widened state asshown in FIG. 7A and FIG. 7B , the pinion gear 203β is rotated rightwardand pulls the movable rack 234β to the driving source unit 205 side.With this arrangement, the moving block 110-3 moves to the right.

When the moving block 110-3 moves to the right, the pinion gear 231α inmesh with the fixed rack 235α rotates leftward, the idler gear 232αrotates rightward and the speed-increasing pinion gear 233α rotatesleftward. The leftward rotation of the speed-increasing pinion gear 233αpulls the movable rack 241α to the moving block 110-3 side. With thisarrangement, the moving block 110-4 moves to the right.

In this manner, with the moving blocks 110-1, 110-2 moving to the leftand the moving blocks 110-3, 110-4 moving to the right, the narrowedstate as shown in FIG. 8A and FIG. 8B is achieved.

When the driving gear 201 α is rotated rightward by the servomotor 206of the driving source unit 205 in the narrowed state as shown in FIG. 8Aand FIG. 8B , the gear elements move in reverse directions to make themoving blocks 110-1, 110-2 move to the right and the moving blocks110-3, 110-4 move to the left to achieve the widened state as shown inFIG. 7A and FIG. 7B.

With respect to the plate width direction (horizontal direction) of thestrips, in the widened state of FIG. 3, when the distance from thecentral position CL of the plate crossbow correction device 100 to themoved position of the moving block 110-1 is defined as L12 and thedistance from the central position CL to the moved position of themoving block 110-2 is defined as L22, and in the narrowed state of FIG.4, when the distance from the central position CL to the moved positionof the moving block 110-1 is defined as L11 and the distance from thecentral position CL to the moved position of the moving block 110-2 isdefined as L21, the stroke ratio of the moving block 110-1 and themoving block 110-2 can be expressed by the following equation (1).

Stroke ratio=1+(D1/D2)=(L22−L21)/(L12−L11)   (1)

Similarly, the stroke ratio of the moving block 110-3 and the movingblock 110-4 can also be expressed by the equation (1).

Ultimately, the ratio of the moving distance of the moving blocks 110-2,110-4 with respect to the moving distance of the moving blocks 110-1,110-3 is constant (a preliminarily determined constant ratio).

Namely, the gear ratio of the rack and pinion mechanism of the movingmechanism 200 is determined such that the moving distances of the movingblocks 110-1, 110-2, 110-3 and 110-4, when seen from a central positionof the plate crossbow correction device, become a distance which is incorrespondence with a preliminarily determined stroke ratio.

In this respect, in FIG. 3, W indicates a widened strip width and inFIG. 4, W indicates a narrowed strip width.

A plate width edge position which is a position of one end in the platewidth direction of the strip 2 detected by the plate edge sensor 20 isinput to the control device 30.

In that case, the control device 30 controls the servomotor 206 to movethe moving blocks 110-4 of the correction mechanisms 100F, 100B suchthat from among the plate crossbow correction device 100, a pair ofelectromagnets at which one end side in the plate width direction of thestrip 2 is located, more particularly, an electromagnet M provided inthe moving block 110-4 which is a moving block close to an end portionof the steel plate (strip 2) from among the moving blocks 110 of thecorrection mechanism 100F and an electromagnet M provided in the movingblock 110-4 which is a moving block close to an end portion of the steelplate (strip 2) from among the moving blocks 110 of the correctionmechanism 100B, opposes the one end portion of the strip 2.

Accompanying movements of the moving blocks 110-4, the other movingblocks 110-1, 110-2 and 110-3 are also moved while maintaining therelationship of the stroke indicated by the equation (1).

Simultaneously, the control device 30 controls a current value suppliedto the electromagnets M such that the distances detected by the distancesensors S become a set distance to thereby adjust the electromagneticforce of the electromagnets M applied to the strip 2. With thisarrangement, crossbow of the strips 2 is correct in a contactless mannerand vibration of the strips 2 is suppressed.

Therefore, even when the strips 2 meander or their plate width changes,a pair of electromagnets M on one end side of the plate crossbowcorrection mechanism 100 and a pair of electromagnets M on the other endside correctly oppose the one end portion and the other end portion ofthe strip 2.

FIG. 9 shows a crossbowed state of the strip 2 at a position at whichthe distance sensor S of the plate crossbow correction device 100 isdisposed, wherein the horizontal axis shows the plate width directionposition while the vertical axis shows the plate shape (amount ofcrossbow). The solid line in FIG. 9 shows a crossbowed state of a strip2 after crossbow correction and the dotted line in FIG. 9 shows acrossbowed state of a strip 2 when no crossbow correction has beenperformed.

FIG. 10 shows a crossbowed state of the strip 2 at a position at whichthe wiping nozzle 5 of the plate crossbow correction device 100 isdisposed, wherein the horizontal axis shows the plate width directionposition while the vertical axis shows the plate shape (amount ofcrossbow). The solid line in FIG. 10 shows a crossbowed state of a strip2 after crossbow correction and the dotted line in FIG. 10 shows acrossbowed state of a strip 2 when no crossbow correction has beenperformed.

As shown by the solid lines in FIG. 9 and FIG. 10, when performing platecrossbow correction using electromagnets M in the plate crossbowcorrection device 100 according to the first embodiment, at least a pairof electromagnets M on one end side will correctly oppose an end portionof the strip 2 so that crossbow at both side portions of the strip 2 canbe suppressed.

Further, since the moving positions of the moving blocks move whilemaintaining the relationship indicated by the equation (1) at the timethe moving blocks 110 move, the disposing positions of theelectromagnets M of the moving blocks 110 will be suitable, and platecrossbow of the strip 2 can be reliably suppressed also at positionsother than both end portions of the strip 2.

In the above first embodiment, while the plate crossbow correctiondevice 100 is provided with four pairs of electromagnets M, it mightalso be provided with five pairs of electromagnets M and also six ormore pairs of electromagnets M.

When the number of pairs of electromagnets M is an odd number, aconfiguration is employed in which electromagnets M at a centralposition (a block provided with electromagnets) are not moved.

FIG. 11 shows a crossbowed state of a strip at the time of crossbowcorrection at a position at which a distance sensor is disposed in theplate crossbow correction device provided with five pair ofelectromagnets.

FIG. 12 shows a crossbowed state of a strip at the time of crossbowcorrection at a position at which the wiping nozzle is disposed in aplate crossbow correction device provided with five pair ofelectromagnets.

As shown in both drawings, it can be understood that crossbow can befurther suppressed at particularly the central portion in the platewidth direction by increasing the number of pairs of electromagnets.

FIG. 13 is a characteristic diagram showing a relationship betweennumbers of pairs of electromagnets and plate crossbow at the position atwhich the wiping nozzle is disposed.

As shown in FIG. 13, it can be understood that plate crossbow can beeffectively suppressed when four or more pairs of electromagnets areprovided.

In this respect, while the hot-dip galvanizing line 10 a comprised withthe plate crossbow correction device 100 of the above-described firstembodiment comprises in-bath rolls 4 a, 4 b, it is also possible toconfigure a hot-dip galvanizing line without in-bath rollers when platecrossbow correction can be reliably performed using the plate crossbowcorrection device 100.

Second Embodiment

A plate crossbow correction device 1000 according to the secondembodiment will be explained with reference to FIG. 14 which is a planview and FIG. 15 which is a front view when the device on the frontsurface side is seen from the strip side.

In FIG. 14 and FIG. 15, the configuration of the correction mechanism100F on the front surface side and the correction mechanism 100B on theback surface side are identical to that shown in the first embodiment.

The correction mechanism 100F on the front surface side is arranged tobe movable along the plate width direction of the strip by means of anoverall moving mechanism 1100 on the front surface side. The correctionmechanism 100B on the back surface side is arranged to be movable alongthe plate width direction of the strip by means of an overall movingmechanism 1200 on the back surface side.

The overall moving mechanism 1100 on the front surface side is comprisedof a main frame 1101 and moving and supporting devices 1102, 1103 forsupporting the main frame 1101 at both ends of the main frame 1101 to bemovable along the plate width direction of the strip. The main frame1101 supports the correction mechanism 100F.

Therefore, when the main frame 1101 moves along the plate widthdirection of the strip, the correction mechanism 100F moves as a wholein the same direction.

The overall moving mechanism 1200 on the back surface side is comprisedof a main frame 1201 and moving and supporting devices 1202, 1203 forsupporting the main frame 1201 at both ends of the main frame 1201 to bemovable along the plate width direction of the strip. The main frame1201 supports the correction mechanism 100B.

Therefore, when the main frame 1201 moves along the plate widthdirection of the strip, the correction mechanism 100B moves as a wholein the same direction.

In this case, moving operations of the moving and supporting devices1102, 1103, 1202, and 1203 are controlled such that moving directionsand moving distances of the main frame 1101 and the main frame 1201become identical.

In the second embodiment, since the correction mechanisms 100F, 100B canbe moved in the plate width direction of the strip as a whole, thecorrection mechanisms 100F, 100B can be moved in accordance therewitheven if the strips largely meander so that crossbow of the strips can bereliably suppressed.

INDUSTRIAL APPLICABILITY

The present invention can be used for correcting crossbow of strips inmolten metal plating facilities.

What is claimed is:
 1. A plate crossbow correction device including: acorrection mechanism on a front surface side disposed on a front surfaceside of a conveyed steel plate which adjusts electromagnetic forceapplied to the steel plate in accordance with a distance to the steelplate and corrects crossbow of the steel plate, and a correctionmechanism on a back surface side disposed on a back surface side of theconveyed steel plate which adjusts electromagnetic force applied to thesteel plate in accordance with a distance to the steel plate andcorrects crossbow of the steel plate, wherein the correction mechanismon the front surface side and the correction mechanism on the backsurface side respectively comprise a plurality of moving blockscomprised with distance sensors detecting a distance to the steel plateand electromagnets applying electromagnetic force to the steel plate, aguide structure supporting the plurality of blocks to be movable along aplate width direction of the steel plate, and a moving structure movinga moving block close to an end portion of the steel plate from among theplurality of moving blocks along the guide structure and moving theremaining blocks along the guide structure following the moving blockclose to the end portion of the steel plate.
 2. The plate crossbowcorrection device according to claim 1, wherein the moving mechanismincludes a servomotor and a rack and pinion mechanism transmittingdriving force of the servomotor to the plurality of moving blocks andmoving the plurality of moving blocks.
 3. The plate crossbow correctiondevice according to claim 2, wherein the rack and pinion mechanism isarranged in that the gear ratio is determined such that moving distanceseach of the moving blocks move when seen from a central position of theplate crossbow correction device become a distance which is inaccordance with a preliminarily determined stroke ratio.
 4. The platecrossbow correction device according to claim 1, further comprising aplate edge sensor detecting plate width edge positions which arepositions at ends in the plate width direction of the steel plate, and acontrol unit controlling moving operations of the moving mechanism suchthat a moving block close to an end portion of the steel plates fromamong the plurality of moving blocks opposes the plate width edgeposition.
 5. A plate crossbow correction device further including anoverall moving mechanism on the front surface side moving the correctionmechanism on the front surface side according to claim 1 along the platewidth direction of the steel plate, and an overall moving mechanism onthe back surface side moving the correction mechanism on the backsurface side according to claim 1 along the plate width direction of thesteel plate.
 6. A plate crossbow correction method by a plate crossbowcorrection device, wherein a correction mechanism on a front surfaceside disposed on a front surface side of a conveyed steel plate whichadjusts electromagnetic force applied to the steel plate in accordancewith a distance to the steel plate and corrects crossbow of the steelplate, and a correction mechanism on a back surface side disposed on aback surface side of the conveyed steel plate which adjustselectromagnetic force applied to the steel plate in accordance with adistance to the steel plate and corrects crossbow of the steel plate,respectively include a plurality of moving blocks comprised withdistance sensors detecting a distance to the steel plate andelectromagnets applying electromagnetic force to the steel plate, and aguide structure supporting the plurality of blocks to be movable along aplate width direction of the steel plate, wherein a moving block closeto an end portion of the steel plate from among the plurality of movingblocks is moved along the guide structure and the remaining movingblocks are moved along the guide structure following movements of themoving block close to the end portion of the steel plate.
 7. The platecrossbow correction method according to claim 6, wherein the pluralityof moving blocks are moved such that moving distances each of the movingblocks move when seen from a central position of the plate crossbowcorrection device become a distance which is in accordance with apreliminarily determined stroke ratio.
 8. The plate crossbow correctionmethod according to claim 6, wherein plate width edge positions whichare positions at ends in the plate width direction of the steel plateare detected, and a moving block close to an end portion of the steelplate from among the plurality of moving blocks is moved to a positionopposing the plate width edge position.